Was perusing some online solar stores and came across a site that gave an example, for very long wire runs, of connecting four (nominal) 12v solar panels in series to feed 48v into a MPPT controller to eliminate power losses and voltage drop. The controller would then convert the 48v to charge a 12v bank of house batteries.
This got me thinking - is it feasible to use a (nominal) 24v solar panel(s) to charge my 12v house batteries through a suitable MPPT charger. My thinking is that in cloudy/hazy weather the output from a 24v panel would be close to a 12v panel in ideal conditions, notwithstanding that in those ideal conditions much of the 24v output would probably go to waste.
Would this work, or is there a glaring hole in my cunning plan?
oldbobsbus said
08:42 AM Apr 12, 2014
There would be no problems using 24v panels as far as I can see so long as you connect your batteries to the controller first...
as for the efficiency I don't think it would make a great deal of difference..
oldtrack123 said
04:48 PM Apr 12, 2014
HI
No problem, But make sure the MPPT reg can take the 24V panel peak voltage [usually around 34V] as well as being suitable for charging 12V batterries
Yes, it can reduce the need for heavier cables using 24V between the panel & the regulator, but that is still an energy waster
The difference in cable costs for short runs would be insignicant
Better to use the MPPT to make gains on cloudy days etc
Just remember that unless the Reg has a seperate voltage senser lead [from the battery to the reg] ,it is best for the reg to be as close as practical to the batterries.
PeterQ
Joe50 said
01:19 AM Apr 13, 2014
Thanks for the replies guys, thought the situation would be along those lines. Will stick to the KISS principle.
Jaahn said
09:03 AM Apr 13, 2014
jpw50 wrote:
To all of the solar gurus out there ....
Was perusing some online solar stores and came across a site that gave an example, for very long wire runs, of connecting four (nominal) 12v solar panels in series to feed 48v into a MPPT controller to eliminate power losses and voltage drop. The controller would then convert the 48v to charge a 12v bank of house batteries.
This got me thinking - is it feasible to use a (nominal) 24v solar panel(s) to charge my 12v house batteries through a suitable MPPT charger. My thinking is that in cloudy/hazy weather the output from a 24v panel would be close to a 12v panel in ideal conditions, notwithstanding that in those ideal conditions much of the 24v output would probably go to waste.
Would this work, or is there a glaring hole in my cunning plan?
Hi JPW50,
Yes you should gain some charging when it is cloudy/hazy. If the normal solar panels output drop below the battery voltage then there is no charging. With the panels in series for the higher voltage then some small current is available, limited though by the low sun power.
However the output when in full sun will still be good with the MPPT regulator as it converts the full power available to charging for the 12v battery. In fact it will be better than a normal regulator as it extracts the best power out of the panels. No waste will occure.
I am currently redoing my solar setup to achieve this very thing. Instead of using my loose panels on the ground I have brought some panels to put on the roof and will be wiring them in series to double the required voltage and into a MPPT to charge the house batteries. I hope this will compensate for some shading and poor sun etc better than a normal setup.
To all of the solar gurus out there ....
Was perusing some online solar stores and came across a site that gave an example, for very long wire runs, of connecting four (nominal) 12v solar panels in series to feed 48v into a MPPT controller to eliminate power losses and voltage drop. The controller would then convert the 48v to charge a 12v bank of house batteries.
This got me thinking - is it feasible to use a (nominal) 24v solar panel(s) to charge my 12v house batteries through a suitable MPPT charger. My thinking is that in cloudy/hazy weather the output from a 24v panel would be close to a 12v panel in ideal conditions, notwithstanding that in those ideal conditions much of the 24v output would probably go to waste.
Would this work, or is there a glaring hole in my cunning plan?
as for the efficiency I don't think it would make a great deal of difference..
HI
No problem, But make sure the MPPT reg can take the 24V panel peak voltage [usually around 34V] as well as being suitable for charging 12V batterries
Yes, it can reduce the need for heavier cables using 24V between the panel & the regulator, but that is still an energy waster
The difference in cable costs for short runs would be insignicant
Better to use the MPPT to make gains on cloudy days etc
Just remember that unless the Reg has a seperate voltage senser lead [from the battery to the reg] ,it is best for the reg to be as close as practical to the batterries.
PeterQ
Hi JPW50,
Yes you should gain some charging when it is cloudy/hazy. If the normal solar panels output drop below the battery voltage then there is no charging. With the panels in series for the higher voltage then some small current is available, limited though by the low sun power.
However the output when in full sun will still be good with the MPPT regulator as it converts the full power available to charging for the 12v battery. In fact it will be better than a normal regulator as it extracts the best power out of the panels. No waste will occure.
I am currently redoing my solar setup to achieve this very thing. Instead of using my loose panels on the ground I have brought some panels to put on the roof and will be wiring them in series to double the required voltage and into a MPPT to charge the house batteries. I hope this will compensate for some shading and poor sun etc better than a normal setup.
Cheers jaahn